From the origins of the name, to their formation within the earth's crust, to the mistaken belief that they are purveyors of bad luck to the optical phenomenon that produces such a mesmerizing and tantalizing array of spectral colours and patterns, opal is indeed a 'stone of mystery'.
gold, to the Maoris of New Zealand.
Topics covered in the course include their physical and optical properties, geological formation, crystal systems, chemical composition, varieties and classification, cause of colour, absorption spectra, common inclusions, fluorescence, mining, grading criteria, methods of synthesis, gem identification, common treatments and enhancements, cleaning and care instructions, and pricing.